1. Field of the Invention
The present invention relates generally to lighting systems, and in particular to an automated lighting system with extendable and retractable light units controlled by a centralized control system.
2. Description of the Related Art
Lighting systems are available in a wide variety of designs, which accommodate various lighting applications and environments. For example, fixed-position lighting systems are commonly used for applications with relatively constant conditions. Other lighting systems can be repositioned as needed for particular illumination tasks. Both fixed-position and movable lighting systems are used for indoor and outdoor applications. Outdoor lighting applications present several challenges to the designer. For example, ambient weather conditions must be considered and can include precipitation, temperature extremes, ultraviolet (UV) radiation, etc.
Another consideration affecting lighting design relates to concealing and/or otherwise protecting the lighting fixtures or units when they are not being used. For example, landscape lights are generally associated with exterior applications and can be used for illuminating and accentuating landscape designs. Low voltage power supplies (e.g., 12 V) are commonly used to reduce electrical shock hazards and to enable multiple light units to receive power via light gauge electrical leads from common power sources. Such power sources are commonly connected to the power systems of buildings and the transformed electrical power is distributed to multiple lighting units around the premises. For example, a common application for low-voltage lighting systems relates to illuminating walkways, driveways and other circulation structures for pedestrians and vehicles. Such light fixtures can be conveniently installed in the ground with the wiring runs between the power source and the fixtures buried below grade. Ground-mounted systems can effectively illuminate the ground-level surfaces of circulation structures such as driveways and walkways, and are particularly effective and attractive in applications not requiring general illumination.
In many applications, particularly outdoors, it would be advantageous to retract the light fixtures below grade for protection from surface traffic, such as vehicles, pedestrians and maintenance equipment. Maintenance, such as mowing, snow removal, etc., can be performed more efficiently if the light fixtures are temporarily retracted into below-grade receptacles.
Such extendable and retractable fixtures have previously been proposed. For example, U.S. Pat. Nos. 5,075,834; 5,513,085; 5,068,773; 5,072,345 and 5,124,902 all show retractable light fixtures. However, heretofore there has not been available an extendable/retractable light fixture with the advantages and features of the present invention.